Para-coumaric acid or para-hydroxycinnamic acid derivatives and their use in cosmetic or dermatological compositions

ABSTRACT

The invention relates to the use of para-coumaric acid or para-hydroxycinnamic acid derivatives in cosmetic or dermatological compositions, specifically to the use of at least one compound derived from para-coumaric acid having a general formula (I) below: 
                         
in which, especially, Z represents an oxygen or an —NH— group; X and Y are identical and each represent a CH or CH 2  group, as an active principle with depigmenting, free-radical-scavenging and/or antiinflammatory activity. The invention also relates to the use of the above compounds for cosmetic care or for the preparation of a pharmaceutical composition, especially for depigmenting an area of skin, having antiradical and/or antiinflammatory activity.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/152,718, filed Jun. 3, 2011, which is a continuation of U.S.application Ser. No. 11/594,440, filed Nov. 8, 2006, which claimspriority from French patent application serial number 0511364, filedNov. 8, 2005, the entire contents of each of which are herebyincorporated by reference in this application.

FIELD OF THE INVENTION

The present invention relates essentially to the use of at least onepara-coumaric (also referred to as “p-coumaric”) acid derivative as anactive agent for the manufacture of a cosmetic or pharmaceutical, andespecially a dermatological or topical composition, with depigmentingactivity or with an inhibitory effect on melanogenesis, and/or withantiradical and/or antiinflammatory activity.

The invention also covers cosmetic compositions or pharmaceutical andespecially dermatological compositions, thus obtained, with depigmentingactivity or with an inhibitory effect on melanogenesis, and/or withantiradical and/or antiinflammatory activity.

The invention also covers a cosmetic care process or a therapeuticdepigmentation treatment process using p-coumaric acid derivatives asdepigmenting active agents.

The invention also covers a cosmetic care process or a therapeutictreatment process for obtaining an antiradical and/or antiinflammatoryeffect using the abovementioned p-coumaric acid derivatives.

BACKGROUND OF THE INVENTION

To combat solar radiation, the skin has differentiated cells that areparticularly suited to this function: the melanocytes. In the course ofa complex process, melanogenesis, these cells manufacture melanin, adark pigment which has the effect of protecting the skin structures andof increasing the time required to contract a solar erythema. However,not all melanins are protective. In particular, there exists one form ofmelanin, known as phaeomelanin, that is extremely phototoxic. Like allmelanins, it is capable of reacting with certain forms of free radicals,but it can also cause the formation of free radicals that are even moretoxic, and which are liable to cause irreversible damage to the geneticmaterial of keratinocytes. Moreover, certain disorders associated withdysfunction of the melanization unit are liable to causehyperpigmentation, which is occasionally particularly unsightly.

Thus, the use of melanin synthesis inhibitors is particularlyadvantageous in cosmetology, not only for applications in which truedepigmentation is desired, as in the case of the bleaching of highlypigmented skin or the inhibition of hyperpigmentation in certainunaesthetic aspects, for example, but also for applications forlightening the complexion and for giving luminosity to the skin andradiance to the surface tissues. This inhibition of melanin synthesismay also be particularly advantageous in the context of therapeutictreatment for treating a true pathology.

para-Coumaric or para-hydroxycinnamic acids have been described asinhibitors of melanin production in numerous studies. However, thesesubstances do not make it possible to obtain significant inhibitoryeffects on melanin synthesis. This excessively weak activity does notmake it possible to obtain strong enough effects and these substancesare thus little used in cosmetic or pharmaceutical topical applicationsfor effectively combating unsightly pigmentations.

The prior art mentions in particular the use of vitamin C (orderivatives thereof) or kojic acid (or derivatives thereof) forinhibiting tyrosinase, but these molecules are either cytotoxic at theconcentration used, or of little efficacy. It is known practice inparticular to use ferulic acid or caffeic acid as depigmenting agent incosmetic compositions. However, these compositions are not entirelysatisfactory as regards the efficacy of the depigmenting action.

Thus, an aim of the present invention is essentially to solve thetechnical problem that consists in providing a depigmenting agent thatis more active than those currently used, such as caffeic acid orferulic acid.

Another aim of the present invention is also to provide compositionsusing these depigmenting agents, cosmetic care methods and/orpharmaceutical treatment methods using these depigmenting agents, andalso the use of these depigmenting agents to exert antiradical and/orantiinflammatory activity.

A further aim of the present invention is also to provide compositionswhose active compounds are extracted from plants.

Yet a further aim of the present invention is also to providecompositions that can be applied topically.

An additional aim of the present invention is also to providedepigmenting agents for combating skin hyperpigmentation, especially foraesthetic purposes, mainly when the skin has at least one hyperpigmentedlocalized area.

A further aim of the present invention is to solve the technicalproblems mentioned above in a safe and reliable way and especially whileavoiding undesirable side effects, particularly in human beings, forexample by reducing the cytotoxicity of the active agents used.

SUMMARY OF THE INVENTION

The present invention solves the problems mentioned above through thesynthesis of novel chemical derivatives of para-coumaric acid, inparticular of caffeic acid, ferulic acid, or even hybrid derivatives ofthese two molecules in certain cases. The inhibitory effect on melaninsynthesis of these novel derivative molecules thus described isextremely strong, the toxicological profile of these molecules isperfect for cosmetic and dermopharmaceutical applications, and theincorporation of these substances into cosmetic or pharmaceuticalformulations is possible without any major problems being encountered.These substances are thus entirely suitable in the context of cosmeticand pharmaceutical applications.

Moreover, by comparing the depigmenting effect of the substancesobtained in accordance with the present invention, which in onepreferred embodiment are para-coumaric acid derivatives grafted ontotyramine, dopamine or tyrosol derivatives, with the effect of compoundsderived from para-coumaric acid, such as caffeic acid or ferulic acid asa mixture with tyramine, dopamine or tyrosol, it was unexpectedly foundthat the activity of the compounds of the present invention is markedlysuperior with reference to said mixture.

Thus, the present invention relates to the use of an effective amount ofat least one compound derived from para-coumaric acid of general formula(I) below:

in which:

-   Z represents an oxygen or an —NH— group;-   X and Y are identical and each represent a CH group (cis or trans)    or CH₂ group;-   n is a number, preferably an integer, ranging from 1 to 12;-   Ra and Rb are identical or different, preferably identical, and    represent a hydrogen atom, a linear or branched acyl group,    preferably of C1-12, a linear or branched, saturated or unsaturated    alkyl group, preferably of C1-12; a salified or non-salified    sulfonyl group (SO₃H); or a salified or non-salified phosphonate    group (PO₃H₂); ORa and/or ORb possibly being in the presence of a    base in dissociated form, for example in a form O—Na+;-   R₁, R₂, R₃, R₄, R₅, R₆, R₇ and R₈ represent, independently of each    other: a hydrogen atom; a hydroxyl group; a halogen atom; a salified    or non-salified acid function; an aldehyde function; an amide    function; an amine function (primary, secondary or tertiary) in    basic or salified form; a cyano group; a thiol group; a nitro group;    a sugar (O-heteroside); a linear or branched alkoxide group,    preferably of C1-12; a linear or branched alkyl chain, preferably of    C1-12; a linear or branched alkenyl chain, preferably of C1-12; a    linear or branched thioalkyl chain, preferably of C1-12; a linear or    branched alkoxy chain, preferably of C1-12; an alkenyloxy chain,    preferably of C1-12; a salified or non-salified sulfate group; a    salified or non-salified sulfonyl group; a salified or non-salified    phosphonate group; a salified or non-salified phosphate group; a    silanol group; in which the carbon-based chains, preferably of    C1-C12, may be substituted;-   as active principle in a cosmetic or pharmaceutical composition. In    a particularly preferred embodiment, the composition is applied    topically. The term “effective amount” as used herein means an    amount of the compound or composition sufficient to significantly    induce a positive benefit, including independently or in    combinations the benefits disclosed herein.

Advantageously, the compounds used are the trans compounds, although theinvention also covers the cis compounds or a cis/trans mixture, whichpreferably comprises a larger amount of trans compounds.

DETAILED DESCRIPTION OF THE INVENTION

In the text hereinbelow, the groups identified generally (Ra, Rb, R1,R2, etc.) refer to any formula comprising the said groups, andespecially to the general formula I. Thus, all combinations that may bemade from the advantageous embodiments are to covered by the presentinvention.

Advantageously, the present invention covers the use of an effectiveamount of at least one compound derived from para-coumaric acid havingthe general formula (I) as defined above, as a depigmenting agent, or asan active principle with antiradical or antiinflammatory activity, in atopical composition. Such topical composition generally further includea dermatologically acceptable carrier. The term “dermatologicallyacceptable” as used herein, means that the compositions or componentsthereof, are suitable for use in contact with human skin tissue withoutundue toxicity, incompatibility, instability, allergic response, and thelike. Such carriers may be approved as acceptable for cosmetic uses,pharmaceutical uses, or both, depending upon the intended uses of thetopical composition being formulated.

Advantageously, Ra and Rb each independently represent a hydrogen atom,a linear or branched C1-12 acyl group, a salified or non-salifiedsulfonyl group (SO₃H); a salified or non-salified phosphonate group(PO₃H₂), and preferably a hydrogen atom.

Advantageously, preferred derivatives are represented by the chemicalformula II, in which the groups R₁ to R₈, X, Y, Z and n represent theelements cited in the formula I:

Advantageously, preferred derivatives are represented by the chemicalformula III, in which the groups R₂, R₃, R₆ and R₇, X, Y, Z and nrepresent the elements cited in the general formula I:

Preferably, the invention covers para-coumaric acid derivatives, knownas ferulic acid derivatives, corresponding to the general formula I inwhich:

-   Ra, Rb, R₁, R₄, R₅ and R₈ preferentially represent a hydrogen,-   R₃ preferentially represents a methoxy group, and R₂ is a hydrogen,-   X and Y each represent a CH group and n is equal to 2,

These derivatives may be represented by the following formulae (IVa andIVb) in which R₆ and R₇ represent the elements cited in the generalformula I:

In the above formulae IVa and IVb, R₆ and R₇ are preferentiallyhydrogens, which corresponds to the derivatives described by formulaeIVa1 and IVb1 below:

Preferably, the compounds also concerned in this invention are thepara-coumaric acid derivatives known as caffeic acid derivatives,corresponding to the general formula I in which: Ra and Rb, R₁, R₂, R₄,R₅ and R₈ preferentially represent a hydrogen, R₃ preferentiallyrepresents a hydroxyl, and R₂ is a hydrogen, X and Y each represent a CHand n is equal to 2. These derivatives are represented by the followingformulae (Va and Vb) in which R₆ and R₇ represent the elements cited inthe general formula

I:

In formulae Va and Vb, R₆ and R₇ are preferentially hydrogens, whichcorresponds to the two derivatives described by formulae Va1 and Vb1below:

The invention also relates to the para-coumaric acid derivativescorresponding to the general formula I in which the substituents Ra, Rb,R₁, R₂, R₃, R₄, R₅, R₆, R₇ and R₈ represent a hydrogen and n ispreferentially equal to 2. Advantageously, R₁, R₄, R₅, and R₈ representa hydrogen. Advantageously, the substituents R₂ and R₃ are chosen from ahydroxyl group, optionally in salified form, or methoxy, and a hydrogenatom. Advantageously, the substituents R₆ and R₇ are chosen from ahydroxyl group, optionally in salified form, or methoxy, and a hydrogenatom. Preferably, n=2. Advantageously, the substituents R₆ and R₇ arechosen from a hydroxyl group, optionally in salified form, and ahydrogen atom.

According to a first embodiment, the para-coumaric acid derivatives areferulic acid derivatives in which Ra, Rb, R₁, R₂ and R₄ preferentiallyrepresent a hydrogen atom; R₃ preferentially represents a methoxy group;X and Y each represent a CH group and n is equal to 2; these derivativespossibly being represented by the following to formulae (IIa and IIb):

in which R₅, R₆, R₇ and R₈ are as defined above. Advantageously, informulae IIa and IIb, R₅, R₆, R₇ and R₈ each represent a hydrogen atom.

According to a second embodiment, in formulae IIa and IIb, R₅, R₆ and R₈each represent a hydrogen atom and R₇ represents a hydroxyl group, whichcorresponds to the two derivatives described by the following formulae:

Advantageously, the para-coumaric acid derivatives are caffeic acidderivatives in which Ra, Rb, R₁, R₂ and R₄ preferentially represent ahydrogen atom; R₃ preferentially represents a hydroxyl group; X and Yeach represent a CH group and n is equal to 2; these derivativespossibly being represented by the following formulae (IIIa and IIIb):

in which:R₅, R₆, R₇ and R₈ are as defined above.

Advantageously, in formulae IIIc and IIIb, R₅, R₆, R₇ and R₈ eachrepresent a hydrogen atom. Advantageously, in formulae IIIc and IIIb,R₅, R₆, R₈ each represent a hydrogen atom and R₇ represents a hydroxylgroup, which corresponds to the two derivatives described by formulaeIIIa1 and IIIb2 below:

Advantageously, the substituents Ra, Rb, R₁, R₂, R₄, R₅, R₆, R₇ and R₈each represent a hydrogen atom, R₃ represents a hydroxyl group, n isequal to 2, these derivatives possibly being represented by thefollowing formulae (VIa and VIb) in which X and Y are CH or CH₂ groups:

According to one advantageous embodiment, the compound is extracted froma plant, said extract preferably comprising a compound chosen from:

It is entirely advantageous to use, in particular in cosmetics, naturalcompounds, in particular derived from plants, so as to provide userswith a guarantee of the healthy origin of the active compounds used. Aperson skilled in the art also knows the various advantages of usingnatural compounds extracted from plants.

It is advantageous to obtain an extract of plants used as raw materialusing a solvent, preferably a polar solvent, and preferably water, awater/alcohol mixture or polyol, for instance a water/glycol orwater/ethanol mixture, or a polyol, or an alcohol, for instance ethanol.Ethyl acetate or acetone, or any mixture of the solvents mentionedabove, may also be used. The extract is preferably filtered and thendried. It is also possible to perform the extraction with moderateheating, for instance to 45° C. The extraction is preferably performedwith stirring. The extraction processes are well known to those skilledin the art. The part of the plants used may vary as a function of theextract to be obtained.

The invention relates in particular to the use of the compoundsmentioned above for exerting depigmenting activity or an inhibitoryeffect on melanogenesis, especially via topical application to at leastone area of skin tissue of an individual.

The invention relates in particular to the use of the compoundsmentioned above for reducing the pigmentation of the said area of skintissue.

The invention also relates to a cosmetic care process, comprising thetopical application of a composition as defined above. The term “topicalapplication”, as used herein, means to apply or spread the compositionsof the present invention onto the surface of skin tissue. Such cosmeticcare processes include methods of

Advantageously, the cosmetic care makes it possible to reduce thepigmentation of the skin in the area of application.

The invention also relates to the formulation of topically appliedcosmetic compositions comprising the para-coumaric derivative compoundsdescribed herein. These cosmetic compositions generally furthercomAdditionally, as a large number of cosmetic active ingredients areknown in the art to improve the health and/or physical appearance of theskin, the skilled artisan will also recognize that it is useful toformulate cosmetic compositions capable of providing multiple benefitsto the skin of an individual, and further, that the compounds describedherein may have a synergistic effect when combined with one or moreadditional cosmetic active ingredients. Thus, cosmetic compositionscomprising the compounds described herein may further compriseadditional cosmetic active ingredients. Preferably, as the compositionis to be in contact with human skin tissue, the additional componentsshould be suitable for application to such tissue, that is, whenincorporated into the composition they are suitable for use in contactwith human skin tissue without undue toxicity, incompatibility,instability, allergic response, and the like within the scope of soundmedical judgment. The CTFA Cosmetic Ingredient Handbook, Second Edition(1992) describes a wide variety of non-limiting cosmetic andpharmaceutical ingredients commonly used in the skin care industry,which are suitable for use in the topical compositions of the presentinvention. Examples of these ingredient classes include, but are notlimited to: abrasives, absorbents, aesthetic components such asfragrances, pigments, colorings/colorants, essential oils, skinsensates, astringents, etc. (e.g., clove oil, menthol, camphor,eucalyptus oil, eugenol, menthyl lactate, witch hazel distillate),anti-acne agents, anti-caking agents, antifoaming agents, antimicrobialagents (e.g., iodopropyl butylcarbamate), antioxidants, binders,biological additives, buffering agents, bulking agents, chelatingagents, chemical additives, colorants, cosmetic astringents, cosmeticbiocides, denaturants, drug astringents, external analgesics, filmformers or materials, e.g., polymers, for aiding the film-formingproperties and substantivity of the composition (e.g., copolymer ofeicosene and vinyl pyrrolidone), opacifying agents, pH adjusters,propellants, reducing agents, sequestrants, skin bleaching andlightening agents (e.g., hydroquinone, kojic acid, ascorbic acid,magnesium ascorbyl phosphate, ascorbyl glucosamine), skin-conditioningagents (e.g., humectants, including miscellaneous and occlusive), skinsoothing and/or healing agents (e.g., panthenol and derivatives (e.g.,ethyl panthenol), aloe vera, pantothenic acid and its derivatives,allantoin, bisabolol, and dipotassium glycyrrhizinate), skin treatingagents, thickeners, and vitamins and derivatives thereof.

The invention also relates to the use of an effective amount of at leastone compound as defined above for the preparation of a pharmaceuticalcomposition for exerting depigmenting activity or an inhibitory effecton melanogenesis, especially via topical application to at least onearea of skin tissue of an individual with hyperpigmentation.

The invention also relates to the use of an effective amount of at leastone compound as defined above for the preparation of a cosmetic orpharmaceutical composition for exerting antiradical and/orantiinflammatory activity. Specifically, by virtue of their antiradicalactivity, the compounds derived from the invention can reduce the L-dopamolecule so as to stop its oxidation into chromophoric compound. Byvirtue of their high antiradical activity, the compounds derived fromthe invention are antiinflammatory compounds: specifically, the freeradicals generated during a UV stress or the like induce theinflammation cascade. This is why compounds with antiradical propertiesinhibit the inflammation cascade.

The invention relates in particular to the following preferredcompounds, which are particularly illustrated.

However, other aims, characteristics and advantages of the inventionwill emerge clearly to a person skilled in the art after reading theexplanatory description that refers to the examples, which are givenpurely as illustrations and should not be considered as limiting thescope of the invention in any way.

The examples form an integral part of the present invention and anycharacteristic appearing novel relative to any prior art from thedescription taken in its entirety, including the examples, forms anintegral part of the invention in its function and in its generality.Thus, each example has a general scope.

Moreover, in the examples, all the percentages are given on a weightbasis, unless otherwise indicated, and the temperature is expressed indegrees Celsius unless otherwise indicated, and the pressure isatmospheric pressure, unless otherwise indicated.

EXAMPLES I—Ferulic acid (4-hydroxy-3-methoxycinnamic acid) derivativesExample 1 N-trans-feruloyldopamine(SO-I-146)

A solution of ferulic acid (300 mg; 1.54 mmol) and of triethylamine (1.5eq; 2.31 mmol) in DMF (3.5 mL) is cooled to 3 or 4° C. using an icebath. An amine, 3-hydroxytyramine (dopamine) (1 eq; 1.54 mmol) is addedto the medium, followed by addition of a solution of BOP(benzotriazol-1-yloxy)tris(dimethylamino)phosphoniumhexafluorophosphate; (1 eq; 1.54 mmol) in dichloromethane (3.5 mL); themixture is stirred for about thirty minutes in the ice bath and then for20 hours at room temperature. Stirring is then stopped and thedichloromethane is evaporated off under vacuum. 30 mL of water are addedto the remaining solution and the mixture obtained is extracted withethyl acetate (3×75 mL). The organic phase is successively washed with100 mL of 1N HCl solution, 100 mL of water and 100 mL of 1M sodiumbicarbonate (NaHCO₃) solution. It is then dried over sodium sulfate andevaporated to dryness. The product obtained is in the form of a whiteprecipitate after chromatography on a column of silica gel.

Example 2 N-trans-feruloyl-3,4-dimethoxydopamine

The protocol derived from Example 1 is applied with ferulic acid and2-(3,4-dimethoxyphenyl)ethylamine instead of ferulic acid and dopamine;the compound obtained is N-trans-feruloyl-3,4-dimethoxydopamine.

Example 3 N-trans-feruloyltyramine

The protocol derived from Example 1 is applied with ferulic acid andtyramine instead of ferulic acid and dopamine; the compound obtained isN-trans-feruloyltyramine.

Example 4 N-trans-feruloyl-4-hydroxy-3-methoxyphenylmethylamine

The protocol derived from Example 1 is applied with ferulic acid and4-hydroxy-3-methoxybenzylamine instead of ferulic acid and dopamine; thecompound obtained isN-trans-feruloyl-4-hydroxy-3-methoxyphenylmethylamine.

Example 5 N-dihydroferuloyltyramine

The protocol derived from Example 1 is applied with dihydroferulic acidand tyramine instead of ferulic acid and dopamine; the compound obtainedis N-dihydroferuloyltyramine.

Example 6 N-dihydroferuloyldopamine

The protocol derived from Example 1 is applied with dihydroferulic acidand 3-hydroxytyramine instead of ferulic acid and dopamine; the compoundobtained is N-dihydroferuloyldopamine.

Example 7 Synthesis of a ferulic acid ester:2-(p-hydroxyphenylethyl)trans-ferulate

Ferulic acid (4-hydroxy-3-methoxycinnamic acid, 250 mg, 1.28 mmol) isdissolved in dichloromethane (10 mL) and DMAP (dimethylaminopyridine,157 mg; 1.28 mmol) is added. After dissolving the two products, tyrosol(353.7 mg; 2.56 mmol) is added, followed by addition of EDCI[1-(3-dimethylaminopropyl)-3-ethylcarbodiimide; 368 mg; 1.92 mmol]. Themixture obtained is stirred for 20 hours at room temperature. Thereaction medium is then diluted with ethyl acetate (32 mL) and water (6mL). The organic phase is separated from the aqueous phase, which isre-extracted with ethyl acetate. The organic phases are combined, driedover magnesium sulfate, washed with saturated NaCl solution andevaporated to dryness. The product is obtained in the form of a whiteprecipitate after chromatography on a column of silica gel, using a 5/5ethyl acetate/cyclohexane mixture.

Example 8 2-(3,4-dihydroxyphenylethyl)trans-ferulate

The protocol derived from Example 7 above is applied with ferulic acidand 3-hydroxytyrosol instead of ferulic acid and tyrosol; the compoundobtained is 3,4-dihydroxyphenylethyl trans-ferulate (formula IVb2)

II—Caffeic acid (3,4-dihydroxycinnamic acid) derivatives Example 9N-trans-caffeoyltyramine

A solution of caffeic acid (300 mg; 1.66 mmol) and of triethylamine (1.5eq; 2.49 mmol) in DMF (3.5 mL) is cooled to 4° C. using an ice bath. Anamine, tyramine (1 eq; 1.66 mmol) is added to the medium, followed byaddition of a solution of BOP(benzotriazol-1-yloxy)tris(dimethylamino)phosphoniumhexafluorophosphate; 1 eq; 1.66 mmol) in dichloromethane (3.5 mL); themixture is stirred for about thirty minutes in the ice bath and then for20 hours at room temperature. Stirring is then stopped and thedichloromethane is evaporated off under vacuum. 30 mL of water are addedto the remaining solution and the mixture obtained is extracted withethyl acetate (3×75 mL). The organic phase is successively washed with100 mL of 1N HCl solution, 100 mL of water and 100 mL of 1M sodiumbicarbonate (NaHCO₃) solution. It is then dried over sodium sulfate andevaporated to dryness. The product is obtained in the form of a whiteprecipitate after purification by chromatography on a column of silicagel.

Example 10 N-trans-caffeoyldopamine

The protocol derived from Example 9 is applied with caffeic acid and3-hydroxytyramine (dopamine) instead of caffeic acid and tyramine; thecompound obtained is N-trans-caffeoyldopamine.

Example 11 N-trans-caffeoyl-4-hydroxy-3-methoxyphenylmethylamine

The protocol derived from Example 9 is applied with caffeic acid and4-hydroxy-3-methoxybenzylamine instead of caffeic acid and tyramine; thecompound obtained is N-trans-caffeoyl-4-hydroxy-3-methoxyphenylmethylamine.

Example 12 N-trans-caffeoyl-3,4-dimethoxydopamine

The protocol derived from Example 9 is applied with caffeic acid and2-(3,4-dimethoxyphenyl)ethylamine instead of caffeic acid and tyramine;the compound obtained is N-trans-caffeoyl-3,4-dimethoxydopamine.

Example 13 dihydrocaffeoyltyramine

The protocol derived from Example 9 is applied with3-(3,4-dihydroxyphenyl)propionic acid and tyramine instead of caffeicacid and tyramine; the compound obtained is dihydrocaffeoyltyramine.

Example 14 Synthesis of a caffeic acid ester: 2-(4-hydroxyphenyl)ethyltrans-caffeoate (formula IVb1)

The protocol derived from Example 7 is applied with caffeic acid andtyrosol instead of ferulic acid and tyrosol; the compound obtained is2-(4-hydroxyphenylethyl) trans-caffeoate (formula IVb1).

Example 15 2-(3,4-dihydroxyphenyl)ethyl trans-caffeoate (formula IVb2)

The protocol derived from Example 14 above is applied with caffeic acidand 3-hydroxytyrosol instead of caffeic acid and tyrosol; the compoundobtained is 2-(3,4-dihydroxyphenylethyl)trans-caffeoate (formula IVb2).

III—COUMARIC ACID 4-hdroxycinnamic acid) DERIVATIVES Example 16N-dihydrocoumaroyltyramine

A solution of 3-(4-hydroxyphenyl)propionic acid or p-dihydrocoumaricacid (1 g; 6.02 mmol) and of triethylamine (1.5 eq; 9.03 mmol) in DMF(10 mL) is cooled to 4° C. using an ice bath. An amine, tyramine (1 eq;6.02 mmol) is added to the medium, followed by addition of a solution ofBOP (benzotriazol-1-yloxy)tris(dimethylamino)phosphoniumhexafluorophosphate (1 eq; 6.02 mmol) in dichloromethane (10 mL); themixture is stirred for about thirty minutes in the ice bath and then for20 hours at room temperature. Stirring is then stopped and thedichloromethane is evaporated off under vacuum. 100 mL of water areadded to the remaining solution and the mixture obtained is extractedwith ethyl acetate (3×75 mL). The organic phase is successively washedwith 100 mL of 1N HCl solution, 100 mL of water and 100 mL of 1M sodiumbicarbonate (NaHCO₃) solution. It is then dried over sodium sulfate andevaporated to dryness. The product is obtained in the form of a whiteprecipitate after purification by chromatography on a column of silicagel.

Example 17 (Ester of para-coumaric acid): 2-(4-hydroxyphenyl)ethyltrans-coumarate

The protocol derived from Example 7 above is applied with p-coumaricacid and tyrosol instead of ferulic acid and tyrosol; the compoundobtained is 2-(4-hydroxyphenyl)ethyl trans-coumarate (formula VIb, X andY are CH)

Example 18 2-(4-hydroxyphenyl)ethyl dihydrocoumarate

The protocol derived from Example 7 above is applied withp-dihydrocoumaric acid (or phloretic acid) and tyrosol instead offerulic acid and tyrosol; the compound obtained is2-(4-hydroxyphenyl)ethyl dihydrocoumarate (formula VIb, X and Y are CH₂)

Example 19N-3-(4-phosphatephenyl)propanoyl-2-(4-phosphatephenyl)ethylamine

The product of Example 16 (180 mg; 0.63 mmol) and sodium hydride (37.8mg; 1.57 mmol; 2.5 eq) are dispersed in 4 mL of anhydrous DMF (2 mL)under argon. The mixture obtained is stirred vigorously for 30 minutesat 0° C., and 1 mL of a solution of diethyl phosphate chloride (273 μL,3 eq) in DMF (1 mL) is then added. Stirring is continued overnight. Thereaction medium is poured into 10 mL of ice-water and extracted withethyl acetate (2×10 mL). The organic phase is dried over sodium sulfateand evaporated to dryness to give a pale residue.

The residue obtained above (300 mg) is dissolved in 3 mL of anhydrousdichloromethane and the solution obtained is cooled to 0° C. An excessof trimethylsilyl bromide (1 mL) is added dropwise with stirring, andstirring is continued for 4 hours at room temperature. The solvent isthen evaporated off under vacuum. The product is obtained in the form ofa white precipitate after purification by reverse-phase chromatographyin 85/15 water/methanol and freeze-drying of the column fractions.

Example 20N-trans-3-(3-methoxy-4-phosphatephenyl)propenoyl-2-(4-phosphatephenyl)ethylamine

The protocol of Example 19 is applied to the product derived fromExample 1; the compound obtained isN-trans-3-(3-methoxy-4-phosphatephenyl)propenoyl-2-(4-phosphatephenyl)ethylamine.

Example 21N-trans-3-(3,4-diphosphatephenyl)propenoyl-2-(4-phosphatephenyl)ethylamine

The protocol of Example 19 is applied to the product derived fromExample 9; to the compound obtained isN-trans-3-(3,4-diphosphatephenyl)propenoyl-2-(4-phosphatephenyl)ethylamine

Example 22N-trans-3-(3-methoxy-4-sulfatephenyl)propenoyl-2(4-sulfatephenyl)ethylamine

To a solution of the product derived from Example 3 (150 mg; 0.455 mmol)in 2 mL of DMF is added a complex of pyridine and of sulfur trioxide(2.73 mmol; 6 eq). The solution obtained is stirred for 20 hours at roomtemperature and 4 mL of aqueous sodium bicarbonate solution are thenadded. The product is obtained in the form of a white precipitate afterpurification by reverse-phase column chromatography (water).

Example 23N-trans-3-(3-methoxy-4-sulfatephenyl)propenoyl-2(3,4-disulfatephenyl)ethylamine

The protocol of Example 22 is applied to the product derived fromExample 1; the compound obtained isN-trans-3-(3-methoxy-4-sulfatephenyl)propenoyl-2(3,4-disulfatephenyl)ethylamine.

Example 24 N-3-4-sulfatephenyl)propanoyl-2-(4-sulfatephenyl)ethylamine

The protocol of Example 22 is applied to the product derived fromExample 16; the compound obtained isN-3-(4-sulfatephenyl)propanoyl-2-(4-sulfatephenyl)ethylamine.

Example 25 of the Invention The Invention Relates to Plant Extracts,Known to Contain One of the Para-Coumaric Acid Derivatives Described inthe Above Examples

As has been mentioned in the description, the present invention isadvantageously performed using natural extracts, preferably plantextracts. Table 1 below describes the natural derivatives identified inplants.

TABLE 1 Tyrosol derivatives Formula Plant Family Part p-Hydroxy-phenylethyl trans-p- coumarate

Stefania longa Polygonum orientale Menispermaceae Polygonaceae Aerialparts Fruit p-dihydro- coumaroyl- tyramine

Solanum tuberosum Solanaceae Tuber (periderm) teucrol

Teucrium pilosum Lamiaceae Whole plant p-Hydroxy- phenylethyltrans-ferulate

Stefania longa Polygonum orientale Coptidis Menispermaceae PolygonaceaeRenonculaceae Aerial parts Fruit Rhizome N-trans- feruloyl- tyramine

Hibiscus cannabinus Piper Porcelia macrocarpa Malvaceae PiperaceaeAnnonaceae Bark Fruit Branch N-dihydro- feruloyl- tyramine

Annona cherimola Annonaceae Stalk N-trans- feruloyl- dopamine

Astraphaxis spinosa Polygonaceae — N-trans- caffeoyl- tyramine

Annona montana Limonium sinense Annonaceae Plumbaginaceae Aerial partsRoot N-dihydro- caffeoyl- tyramine

Lycium chinense Solanaceae Root

Thus, various compositions were prepared from the plants of the abovetable. The invention covers any extract from these plants, in particularthe extracts obtained according to Example 26 below.

It is thus preferred to perform an extraction preferably with a polarsolvent or a mixture of polar solvents, optionally at reflux, preferablyof the plant part mentioned in Table 1. Once the extraction has beenperformed, the solution is filtered and optionally redissolved in apolar solvent or a mixture of polar solvents.

Example 26 of the Invention Extractions Performed using Plants known toContain one of the para-coumaric Acid Derivatives Derived from theInvention

Preferably, a Hibiscus cannabinus extract is prepared from chopped barkat 10% (w/w) in refluxing ethanol. The extraction is performed for 1hour and the solution is then filtered, the ethanol is removed and theN-trans-feruloyltyramine (product derived from Example 3) obtained isdissolved to 5% (w/w) in a water/glycol mixture and then ultrafilteredthrough a ceramic filter with different cutoff thresholds, and finallyfiltered at 0.45 μm.

Preferably, a Hibiscus cannabinus extract is prepared from chopped barkat 10% (w/w) in ethyl acetate. The extraction is performed for 1 hourand the solution is then filtered, the ethyl acetate is removed and theN-trans-feruloyltyramine (product derived from Example 3) obtained isdissolved at 5% (w/w) in a water/glycol mixture and then ultrafilteredthrough a ceramic filter with different cutoff thresholds, and finallyfiltered at 0.45 μm.

Preferably, a Hibiscus cannabinus extract is prepared from chopped barkat 10% (w/w) in acetone. The extraction is performed for 1 hour and thesolution is then filtered, the acetone is removed and theN-trans-feruloyltyramine (product derived from Example 3) obtained isdissolved at 5% (w/w) in a water/glycol mixture and then ultrafilteredthrough a ceramic filter with different cutoff thresholds, and finallyfiltered at 0.45 μm.

Preferably, an extract of Hibiscus cannabinus is prepared from choppedbark at 10% (w/w) in a mixture consisting of 75% water and 25% butyleneglycol. The maceration is performed overnight at 45° C. and theN-trans-feruloyltyramine (product derived from Example 3) obtained isthen ultrafiltered through a ceramic filter with different cutoffthresholds, and finally filtered at 0.45 μm.

Preferably, an extract of Lycium chinense is prepared from chopped rootsat 10% (w/w) in refluxing ethanol. The extraction is performed for 1hour and the solution is then filtered, the ethanol is removed and theN-trans-dihydrocaffeoyltyramine (product derived from Example 13)obtained is dissolved at 5% (w/w) in a water/glycol mixture and thenultrafiltered through a ceramic filter with different cutoff thresholds,and finally filtered at 0.45 μm.

Preferably, a Lycium chinense extract is prepared from chopped bark at10% (w/w) in ethyl acetate. The extraction is performed for 1 hour andthe solution is then filtered, the ethyl acetate is removed and theN-trans-dihydrocaffeoyltyramine (product derived from Example 13)obtained is dissolved at 5% (w/w) in a water/glycol mixture and thenultrafiltered through a ceramic filter with different cutoff thresholds,and finally filtered at 0.45 μm.

Preferably, a Lycium chinense extract is prepared from chopped bark at10% (w/w) in acetone. The extraction is performed for 1 hour and thesolution is then filtered, the acetone is removed and theN-trans-dihydrocaffeoyltyramine (product derived from Example 13)obtained is dissolved at 5% (w/w) in a water/glycol mixture and thenultrafiltered through a ceramic filter with different cutoff thresholds,and finally filtered at 0.45 μm.

An extract of Lycium chinense is prepared from chopped bark at 10% (w/w)in a mixture consisting of 75% water and 25% butylene glycol. Themaceration is performed overnight at 45° C. and theN-trans-dihydrocaffeoyltyramine (product derived from Example 13)obtained is then ultrafiltered through a ceramic filter with differentcutoff thresholds, and finally filtered at 0.45 μm.

The other extracts mentioned in Table 1 were also obtained according tothe various protocols mentioned above with reference to the compounds ofExamples 3 and 13. The protocol variations made are directly availableto a person skilled in the art on the basis of his general knowledge.

Example 27 of the Invention In Vitro Test of Inhibition of IsolatedTyrosinase with the p-coumaric Acid Derivatives

Tyrosinase catalyses the formation of L-dopaquinone and then ofdopachrome from L-dopa. Now, dopachrome is a coloured compound that maybe quantified by visible spectrophotometry at 490 nm. The use of anactive agent capable of modifying the enzymatic activity will bereflected by a variation in the optical density at 490 nm. The to ratioof the rates of formation of dopachrome makes it possible to determineprecisely the activations or inhibitions obtained with the various testmolecules.

The sample to be tested is incubated in the presence of fungaltyrosinase (Sigma), for 5 minutes with stirring. L-Dopa (Sigma), atyrosinase substrate, is incubated for 10 minutes in the absence oflight, in the presence or absence of the test molecules. The calculationof the percentage of inhibition is performed by relating the test OD tothe OD of the negative control without molecule. The positive controlused is kojic acid (Sigma) at 0.01%=45%±5% inhibition.

In the context of this in vitro test, the p-coumaric acid derivativeswere tested at final concentrations of 10⁻⁴M and 10⁻⁵M. The resultsobtained are described in Table 2.

TABLE 2 Inhibition of fungal tyrosinase with various para-coumaric acidderivatives at 490 nm, expressed as a percentage of inhibition. MeanMean SD SD Test derivatives 10⁻⁴M 10⁻⁵M 10⁻⁴M 10⁻⁵M Example 11 12.03 3.72.99 2.09 Example 9 27.42 13.06 0.24 1.24 Example 10 16.23 14.72 1.830.87 Example 12 17.32 20.26 1.06 1.19 Example 3 29.41 10.16 1.33 5.37Example 4 1.35 0 1.26 1.02 Example 1 9.18 0 1.65 0.59 Example 2 0 nd2.06 nd SD: standard deviation nd: not determined

It is clearly seen from Table 2 above that the test derivatives inhibittyrosinase even at low concentrations.

Example 28 of the Invention In Vitro Test of Inhibition of HumanTyrosinase with the p-Coumaric Acid Derivatives

Human tyrosinase, obtained from melanocyte extracts obtained fromhealthy donors, catalyses the formation of L-dopaquinone from L-dopa.Now, the L-dopaquinone may be quantified by visible spectrophotometry at490 nm by means of a chromogen: 3-methyl-2-benzothiazolinone hydrazone(MBTH). This reagent traps the o-quinones synthesized by tyrosinase togive a stable and soluble compound MBTH-o-quinone with a high molaroptical density.

Thus, the use of an active agent capable of modifying the enzymaticactivity will be reflected by a variation in the OD at 490 nm comparedwith that obtained in the negative control (100% activity).

The melanocyte extract is obtained after lysis of cell membranes of thenormal human melanocytes, performed via a thermal shock. The supernatantis recovered and then incubated with MBTH (Sigma) and L-dopa (Sigma).The OD at 490 nm measured after 30 minutes is related, for each activeagent tested, to that obtained for the control and the percentage ofinhibition is calculated by relating the test OD (test molecule) to theOD for the negative control (without molecule). The positive controlused is kojic acid at 0.1% (60%±5% inhibition). The results obtained arecollated in Table 3.

TABLE 3 Inhibition of human tyrosinase with the p-coumaric acidderivatives at 490 nm, results expressed as percentage of inhibition.p-Coumaric acid Mean Mean SD SD derivatives 10⁻⁴M 10⁻⁵M 10⁻⁴M 10⁻⁵MExample 11 0 8.68 3.29 1.74 Example 9 22.09 11.88 5.46 3.04 Example 109.91 11.45 2.53 3.28 Example 12 6.53 0 1.88 0.69 Example 3 0 7.56 5.873.43 Example 4 6.42 4.92 0.95 2.52 Example 1 0 0 4.22 5.87 Example 20.94 0 1.92 4.22 It is seen from Table 3 above that the inhibitoryactivity of the para-coumaric acid derivatives is present but modest onthis particular model of isolated human tyrosinase.

Example 29 of the Invention Test of Inhibition of Human TyrosinaseStudied as a Monolayer after Application of the Test Active Agents toNormal Human Melanocytes

Normal human melanocytes (obtained from abdominal surgery) are seeded in24-well plates at a rate of 80 000 cells per well. They are cultured toconfluence and the active agents are applied for 24 hours to the culturemedia. After 24 hours, the media are removed and the melanocytes aredetached via mechanical action. An extraction is performed via a thermalshock and the supernatants are then recovered and incubated with MBTH(Sigma) and L-dopa (Sigma). The OD at 490 nm is measured after 30minutes, and the tyrosinase inhibition is calculated by relating the ODat 490 nm to the protein content (measured in each culture well) of thetest relative to the ratio: OD 490 nm/protein concentration of thenegative control (untreated control). A percentage of anti-tyrosinaseactivity is thus calculated relative to the untreated control. Thenegative control of the experiment is kojic acid applied at 0.1% to themelanocytes (for a measured inhibition of 20%±5%).

TABLE 4 Inhibition of human tyrosinase after application of thep-coumaric acid derivatives and of the commercial products to normalhuman melanocytes, results expressed as percentage of inhibition (nd:not determined). Mean Mean SD SD Compounds 10⁻⁴M 10⁻⁵M 10⁻⁴M 10⁻⁵Mp-Dihydrocoumaric acid 3.74 nd 1.62 nd p-Coumaric acid or 50.07 nd 4.67nd p-hydroxycinnamic acid Tyramine 22.84 nd 3.21 nd Dopamine 10.29 2.4Caffeic acid 10.39 2.34 0.19 3.22 Ferulic acid 11.72 5.87 1.86 14.32Ferulic acid + dopamine 13.86 nd 1.2 nd (as a mixture) Example 7 33.563.48 0.82 4.13 Example 4 39.84 15.76 11.16 9.7 Example 1 62.31 29.432.38 4.69 Example 3 49.62 33.12 3.82 1.38 Example 11 nd 28.03 nd 5.28Example 9 100 24.59 2.41 1.39 Example 10 66.77 0 8.94 4.41 Example 224.59 18.52 4.71 4.22 Example 12 nd 5.63 nd 6.3 Example 5 27.66 nd 7.17nd Example 6 41.79 nd 5.19 nd Example 13 93.86 12.87 2.08 14.78 Example16 96.24 40.71 2.14 4.08

It is clearly seen from the above table that the results obtained inthis model reflect real efficacy of the para-coumaric acid derivativeson the inhibition of human melanogenesis. The percentages of inhibitionobserved are markedly superior to those obtained on a model very remotefrom the human form, i.e. fungal tyrosinase, and by direct contact witha tyrosinase extracted from normal human melanocytes.

The hydroxylated para-coumaric acid derivatives thus show activity thatis particularly unexpected to those skilled in the art and highlysignificant on the inhibition of hyman tyrosinase, whereas the efficacyis reduced on a less pertinent model using a fungal-based tyrosinase,which is widely used and described in the bibliography.

Tyramine and dopamine were tested at 10⁻⁴M (see above table) and showedvery low activity. Molecules derived from the reaction between caffeicacid and tyramine or dopamine (the compounds derived from Examples 9 and10, respectively) made it possible to very significantly increase theanti-tyrosinase activity, all the more so since caffeic acid alone alsoshowed very low activity.

The molecules derived from the reaction between ferulic acid andtyramine or dopamine produce the same effect (the compounds derived fromExamples 1 and 3, respectively), only ferulic acid also being verysparingly active.

The methyl analogue of dopamine makes it possible to obtain aninhibitory effect on melanin synthesis that is measurable but smallerthan that of the non-methyl derivatives. The molecule derived from thereaction between caffeic acid and the methyl analogue of dopamine, onthe one hand (compound derived from Example 12), and that derived fromferulic acid and from the same compound, on the other hand (compoundderived from Example 2), do not allow such high activity.

Example 30 of the Invention Test of Inhibition of Human Tyrosinase afterApplication of the Compounds Derived from Examples 9, 10, 1 and 3 toNormal Human Melanocytes Derived from Various Donors

The compounds derived from the examples mentioned above were tested onmelanocytes derived from various donors but of fair phototype, accordingto the protocol described in Example 29. The donors tested are asfollows:

-   -   donor S (donor tested in Example 12): 46 years old    -   donor 1: 40 years old    -   donor 2: 47 years old    -   donor 3: 33 years old

The results obtained are described in the tables below:

TABLES 5 Inhibition of tyrosinase with the compounds of Examples 9, 10,1 and 3 on 4 different donors. Mean Mean SD SD 10⁻⁴ M 10⁻⁵ M 10⁻⁴ M 10⁻⁵M Example 9 Donor S 100 24.59 1.39 2.41 Donor 1 65.33 0 5.25 28.87 Donor2 61.52 0 5.54 24.31 Donor 3 70.68 22.21 2.1 8.68 Example 10 Donor S66.77 0 8.94 4.41 Donor 1 44.6 0 5.76 9.43 Donor 2 0 0.15 21.69 1.62Donor 3 14.38 3.32 6.64 11.24 Example 1 Donor S 62.31 29.43 2.38 4.69Donor 1 63.89 35.79 4.42 4.54 Donor 2 59.89 12.87 3.54 6.6 Donor 3 50.1718.93 7.72 2.5 Example 3 Donor S 49.62 33.12 3.82 1.38 Donor 1 44.81 08.55 35.85 Donor 2 10.65 0 5.12 4.99 Donor 3 57.89 42.45 7.52 8.9The results obtained show great efficacy of the compounds on 4 differentdonors.

Example 31 of the Invention Test of Inhibition of Human Tyrosinase afterApplication of the Compounds Derived from Examples 3, 9 and 1 to NormalHuman Melanocytes Derived from Various Donors of Brown and BlackPhototypes

The compound derived from Example 1 is tested on cultures of melanocytesobtained from 2 donors of brown phototype and from one donor of blackphototype. The protocol applied is that described in Example 29. Theresults obtained on the 2 donors to of brown phototype are described inTables 6.

TABLES 6 Inhibition of tyrosinase obtained with the compound derivedfrom Example 3 on 2 donors of brown phototype. Mean Mean SD SD Donor ADonor B Donor A Donor B Example 3 10⁻³ M 85.57 87.4 8.36 3.15 10⁻⁴ M40.41 30.49 1.77 3.2 10⁻⁵ M 15.55 16.71 2.03 6.87 Example 9 10⁻³ M 98.8894.46 0.59 5.35 10⁻⁴ M 44.59 44.4 11.49 1.59 10⁻⁵ M 21.29 18.93 1.933.24 Example 1 10⁻³ M 99.38 87.23 0.13 6.01 10⁻⁴ M 59.17 65.77 0.64 5.1910⁻⁵ M 29.27 20.78 2.59 6.14

The results obtained on the brown phototypes show that theanti-tyrosinase activity is dose-dependent and strong. The resultsobtained with the donor of black phototype (31 years old) are describedin Table 7 below.

TABLE 7 Inhibition obtained for the compound derived from Examples 3 and9 on a donor of negroid skin. Mean Negroid skin SD Example 3 10⁻⁴ M 44.53.68 10⁻⁵ M 21.95 4.76 Example 9 10⁻⁴ M 49.33 3.55 10⁻⁵ M 16.01 1.15

The inhibitory activity on tyrosinase derived from the donor withnegroid skin is dose-dependent and conforms the results obtained on theone hand on donors derived from fair phototypes.

Example 32 of the Invention Study of the Cytotoxicity of Para-CoumaricAcid Derivatives

The cytotoxicity of the active agents is studied on normal humanmelanocytes in 24-well plates, via assay with PNPP (P-nitrophenylphosphate), this substance being converted into p-nitrophenol via theintracellular acid phosphatases of viable cells. The absorbance ofp-nitrophenol at 405 nm is directly proportional to the number of viablecells.

The active agents are tested at 2 different concentrations (10⁻⁴ M and10⁻⁵ M) and added to the culture medium and incubated at 37° C. for 24hours. The assay with PNPP is performed on the cell lawn and the resultsare expressed as a percentage of viability relative to the negativecontrol (untreated wells).

The results obtained are collated in Table 8 below:

TABLE 8 Percentages of viability obtained for the various p-coumaricacid derivatives on normal human melanocytes (the molecules were testedat 2 concentrations, 10⁻⁴ and 10⁻⁵ M. Mean Mean SD SD 10⁻⁴ M 10⁻⁵ M 10⁻⁴M 10⁻⁵ M Example 3 102.55 111.54 0.296 0.081 Example 4 101.94 99.550.095 0.191 Example 9 77.9 94.96 0.101 0.147 Example 10 84.62 102.1 0.090.045 Example 11 39.02 116.99 0.039 0.09 Example 12 33.51 109.84 0.0530.111 Example 1 94.49 119.83 0.082 0.083 Example 2 114.29 114.6 0.0430.085

The test molecules are non-cytotoxic when they are tested at molarconcentrations of 10⁻⁴ and 10⁻⁵ M since the percentages of viabilityobtained are greater than 75% viability (tolerated threshold). Only 2molecules have a threshold lower than 75% when tested at 10⁻⁴ M, i.e.the molecules derived from Examples 11 and 12. To be evaluated, thesemolecules will thus need to be tested as a monolayer at concentrationsbelow 10⁻⁴ M (for example 10⁻⁵ M).

Example 33 of the Invention Comparison of the Efficacy of thePara-Coumaric Acid Derivatives and of Quasi-Drug Molecules

A study is performed with molecules known in the literature for theirdepigmenting activity; these molecules are applied to the modeldescribed in Example 29 so as to compare their efficacy relative to themolecules described in the various examples. Vitamin C stabilized with amagnesium phosphate group, or VitC MgP, and kojic acid were evaluated inour model. The results obtained are described in Table 9.

TABLE 9 Tyrosinase inhibition obtained for literature controls. MoleculeMean and test Inhibition concentration (%) SD Cytotoxicity VitC 3% 97.771.15 cell death VitC 0.3% 49.28 4.86 cell death VitC 0.03% 0 7.3 no VitCMgP 3% 0 1.65 no VitC MgP 0.3% 1.55 3.28 no VitC MgP 0.03% 2.93 2.79 noKojic acid 0.5% 25.09 3.2 cell death Kojic acid 0.05% 14.26 4.37 noKojic acid 0.005% 6.84 4.32 noThe test molecules were found to be ineffective in the model describedin Example 29 when compared with the para-coumaric acid derivatives,which are particularly active at much lower concentrations.Specifically, no molecule allowed human tyrosinase to be inhibited at athreshold comparable to that of the para-coumaric acid derivatives.

Vitamin C tested at 3% and 0.3% shows high levels of inhibition sincethis molecule has cytotoxic action on melanocytes and is non-specific.Consequently, this molecule cannot be considered as active in our model.The para-coumaric acid derivatives are found to be molecules that arehighly effective on normal human tyrosinase.

Example 34 of the Invention Study of the Antiradical Activity of thePara-Coumaric Acid Derivatives

The antiradical activity of the derivatives derived from the synthesesdescribed above was evaluated in an in vitro acellular model using DPPH.

1,1-Diphenyl 2-picryihydrazyl, on account of its paramagnetic structure,can accept an electron or a hydrogen radical to become a stablediamagnetic molecule. This free radical, which is purple coloured inethanol, has a strong absorption band at 520 nm.

The addition of a compound that provides electrons results in adecolorization of the 1,1-diphenyl 2-picrylhydrazyl that is proportionalto the number of electrons taken up by the radical, which may bemonitored by measuring the absorbance at 520 nm.

DPPH is incubated for 30 minutes in the presence of the derivativesdescribed above, tested at a concentration of 10⁻⁵M, or alone for thecontrol. At the end of the incubation, the antiradical activity of theabove derivatives is evaluated by measuring the absorbance of thesolution at 520 nm.

The antiradical activity of each test product is calculated according tothe formula, as a percentage:100−((OD₅₂₀ in the presence of the test compound/OD₅₂₀ in the absence ofcompound)×100)

TABLE 10 Antiradical activity of the compounds derived from theinvention: Mean SD Compounds 10⁻⁵ M 10⁻⁵ M Example 4 15.72 2.86 Example1 60.01 8.03 Example 3 13.73 2.03 Example 11 59.2 2.54 Example 9 41.172.60 Example 10 57.45 2.39 Example 2 20.16 0.96 Example 12 44.51 3.45

The compounds described above show antiradical activity, at aconcentration of 10⁻⁵M. On account of their high antiradical activity,the compounds derived from the invention are antiinflammatory compounds:specifically, the free radicals generated during a UV stress or the likeinduce the inflammation cascade. This is why compounds with antiradicalproperties inhibit the inflammation cascade.

The term “products of the invention” means the compounds correspondingto the general formula I, and also the preferred compounds andespecially the compounds described in Examples 1 to 26.

Example 35 of the invention Use of the Products of the Invention inCosmetic or Pharmaceutical Formulations of Oil-in-Water Emulsion Type

Formulation 35a:

A Water qs 100 Butylene Glycol 2 Glycerol 3 Sodium DihydroxycetylPhosphate, 2 Isopropyl Hydroxycetyl Ether B Glycol Stearate SE 14Triisononaoin 5 Octyl Cocoate 6 C Butylene Glycol, Methylparaben, 2Ethylparaben, Propylparaben, pH adjusted to 5.5 D Products of theinvention 0.01-10%Formulation 35b:

A Water qs 100 Butylene Glycol 2 Glycerol 3 Polyacrylamide, Isoparaffin,2.8 Laureth-7 B Butylene Glycol, 2 Methylparaben, Ethylparaben,Propylparaben; Phenoxyethanol, 2 Methylparaben, Propylparaben,Butylparaben, Ethylparaben Butylene Glycol 0.5 D Products of theinvention 0.01-10%Formulation 35c:

A Carbomer 0.50 Propylene Glycol 3 Glycerol 5 Water qs 100 B OctylCocoate 5 Bisabolol 0.30 Dimethicone 0.30 C Sodium Hydroxide 1.60 DPhenoxyethanol, 0.50 Methylparaben, Propylparaben, Butylparaben,Ethylparaben E Fragrance 0.30 F Products of the invention 0.01-10%

Example 36 of the Invention Use of the Products of the Invention in aFormulation of Water-in-Oil Type

A PEG 30- 3 dipolyhydroxystearate Capric Triglycerides 3 CetearylOctanoate 4 Dibutyl Adipate 3 Grape Seed Oil 1.5 Jojoba Oil 1.5Phenoxyethanol, 0.5 Methylparaben, Propylparaben, Butylparaben,Ethylparaben B Glycerol 3 Butylene Glycol 3 Magnesium Sulfate 0.5 EDTA0.05 Water qs 100 C Cyclomethicone 1 Dimethicone 1 D Fragrance 0.3 EProducts of the invention 0.01-10%

Example 37 of the Invention Use of the Products of the Invention in aFormulation of Shampoo or Shower Gel Type

A Xantham Gum 0.8 Water qs 100 B Butylene Glycol, 0.5 Methylparaben,Ethylparaben, Propylparaben Phenoxyethanol, 0.5 Methylparaben,Propylparaben, Butylparaben, Ethylparaben C Citric acid 0.8 D SodiumLaureth Sulfate 40.0 E Produit of the invention 0.01-10%

Example 38 of the Invention Use of the Products of the Invention in aFormulation of Lipstick Type and Other Anhydrous Products

A Mineral Wax 17.0 Isostearyl Isostearate 31.5 Propylene GlycolDipelargonate 2.6 Propylene Glycol Isostearate 1.7 PEG 8 Beeswax 3.0Hydrogenated Palm Kernel Oil 3.4 Glycerides, Hydrogenated PalmGlycerides Lanolin Oil 3.4 Sesame Oil 1.7 Cetyl Lactate 1.7 Mineral Oil,Lanolin Alcohol 3.0 B Castor Oil qs 100 Titanium Dioxide 3.9 CI 15850: 10.616 CI 45410: 1 0.256 CI 19140: 1 0.048 CI 77491 2.048 C Products ofthe invention 0.01-5%

Example 39 of the Invention Use of the Products of the Invention in anAqueous Gel Formulation (Eye Contours, Slimming, Etc.)

A Water qs 100 Carbomer 0.5 Butylene Glycol 15 Phenoxyethanol,Methylparaben, 0.5 Propylparaben, Butylparaben, Ethylparaben B Productsof the invention 0.01-10%

Example 40 of the Invention Use of the Products of the Invention in aFormulation of Triple Emulsion Type

Primary emulsion W1/O

A PEG 30- 4 dipolyhydroxystearate Capric Triglycerides 7.5 Isohexadecane15 PPG-15 Stearyl ether 7.5 B Water 65.3 C Phenoxyethanol, 0.7Methylparaben, Propylparaben, Butylparaben, EthylparabenSecondary emulsion W1/O/W2

A Primary emulsion 60 B Poloxamer 407 2 Phenoxyethanol, 0.3Methylparaben, Propylparaben, 2-bromo-2- nitropropane-1,3-diol Water qs100 C Carbomer 15 D Triethanolamine pH 6.0-6.5

Example 41 of the Invention Preparation of Pharmaceutical FormulationsContaining the Product of the Invention

Formulation 41a: Preparation of Tablets

A Excipients In g per tablet Lactose 0.359 Sucrose 0.240 B Products ofthe invention* 0.001-0.1 *The product of the invention is obtained, forexample, according to the extraction process described in Example 1followed by a drying step.Formulation 41b: Preparation of a Pomade

A Excipients Low-density polyethylene 5.5 Liquid paraffin qs 100 BProducts of the invention* 0.001-0.1 *The product of the invention isobtained, for example, according to the extraction process described inExample 1 followed by a drying step.Formulation 41c: Preparation of an Injectable Formula

A Excipient Isotonic saline solution 5 ml B Products of the invention*0.001-0.1 g *The product of the invention is obtained, for example,according to the extraction process described in Example 1 followed by adrying step.

Example 42 Evaluation of the Cosmetic Acceptance of a PreparationContaining the Product of the Invention

The toxicology tests were performed on the compound obtained accordingto Example 1 incorporated at 10% into a 0.5% xanthan gel, by ocularevaluation on rabbits, by studying the absence of abnormal toxicity viasingle oral administration to rats, and by studying the sensitizingpower on guinea pigs.

Evaluation of the Primary Skin Irritation in Rabbits:

The preparations described above are applied without dilution at a doseof 0.5 ml to the skin of 3 rabbits according to the method recommendedby the OCDE Directive concerning the study of “the acuteirritant/corrosive effect on the skin”. The products are classifiedaccording to the criteria defined by the decree of 1/2/1982 published inthe JORF of 21/02/82. The results of these tests made it possible toconclude that the products of the invention were classified asnon-irritant to the skin.

Evaluation of the Ocular Irritation in Rabbits:

The preparations described above were instilled pure, in a singleapplication, at a rate of 0.1 ml, into the eye of 3 rabbits according tothe method recommenced by the OCDE Directive No. 405 of 24 February 1987concerning the study of the “acute irritant/corrosive effect on theeyes”. The results of this test make it possible to conclude that thepreparations may be considered as non-irritant to the eyes, within themeaning of the Directive 91/326 EC, used pure or without dilution.

Test on the Absence of Abnormal Toxicity Via Single Oral Administrationto Rats:

The preparations described were administered in a single portion orallyat a dose of 2 g/kg of body weight, to 5 male rats and 5 female ratsaccording to a protocol inspired by the OCDE Directive No. 401 of 24February 1987 and adapted to cosmetic products. The LD₀ and LD₅₀ arefound to be greater than 2000 mg/kg. The preparations tested aretherefore not classified among the preparations hazardous by ingestion.

Evaluation of the Skin Sensitization Potential in Guinea Pigs:

The preparations described are subjected to the maximization testdescribed by Magnusson and Kligmann, which protocol is in accordancewith the OCDE guideline No. 406. The preparations are classified as notsensitizing on contact with the skin.

TABLE 11 CHEMICAL FORMULAE Products Structural formulae Tyraminehydrochloride

3-Hydroxytyramine Hydrochloride (Dopamine Hydrochloride)

Examples Formulae Example 3 (N-trans-Feruloyltyramine)

Example 4 (N-trans-Feruloyl-4-hydroxy-3- methoxyphenylmethylamine)

Example 9 (N-trans-Caffeoyltyramine)

Example 10 (N-trans-Caffeoyldopamine)

Example 11 (N-trans-Caffeoyl-4-hydroxy- 3-methoxyphenylmethylamine)

Example 12 (N-trans-Caffeoyl-3,4- dimethoxydopamine)

Example 1 (N-trans-Feruloyldopamine)

Example 2 (N-trans-Feruloyl-3,4- dimethoxydopamine)

Example 5 (N-Dihydroferuloyltyramine)

Example 6 (N-Dihydroferuloyldopamine)

Example 16 (3-(4-Hydroxyphenyl)-N-(2-[4-hydroxyphenyl]ethyl)propanamide)

Example 13 (Dihydrocaffeoyltyramine)

Example 19 N-3-(4-Phosphatephenyl)- propanoyl-2-(4-phosphatephenyl)-ethylamine

Example 20 N-trans-3-(3-Methoxy-4- phosphatephenyl)propenoyl-2-(4-phosphatephenyl)ethylamine

Example 21 N-trans-3-(3,4- Diphosphatephenyl)propenoyl-2-(4-phosphatephenyl)ethylamine

Example Formulae Example 22 N-trans-3-(3-Methoxy-4-sulfatephenyl)propenoyl-2(4- sulfatephenyl)ethylamine

Example 23 N-trans-3-(3-Methoxy-4- sulfatephenyl)propenoyl-2(3,4-disulfatephenyl)ethylamine

Example 24 N-3-(4-Sulfatephenyl)-propanoyl-2-(4-sulfatephenyl)ethylamine

Examples Formulae Example 7 2-(p-Hydroxyphenylethyl) trans-ferulate

Example 8 2-(3,4-Dihydroxyphenylethyl) trans- ferulate

Example 14 2-(4-Hydroxyphenyl)ethyl trans-caffeoate

Example 15 2-(3,4-Dihydroxyphenyl)ethyl trans- caffeoate

Example 17 2-(4-Hydroxyphenyl)ethyl trans- coumarate

Example 18 2-(4-Hydroxyphenyl)ethyl dihydrocoumarate

The invention claimed is:
 1. A method of reducing skin pigmentation,comprising applying to an area of human skin in need of reducedpigmentation a topical composition comprising an amount of a compound offormula (III)

effective to reduce skin pigmentation, wherein Z represents an oxygen oran —NH— group; X and Y are identical and each represent a CH group (cisor trans) or CH₂ group; n is a number, preferably an integer, rangingfrom 1 to 12; R₂, R₃, R₆ and R₇ are, independently of each other: ahydrogen atom; a hydroxyl group; a halogen atom; a salified ornon-salified acid function; an aldehyde function; an amide function; aprimary, secondary, or tertiary amine function in basic or salifiedform; a cyano group; a thiol group; a nitro group; a sugar; anO-heteroside; a linear or branched alkoxide group; a linear or branchedalkyl chain; a linear or branched alkenyl chain; a linear or branchedthioalkyl chain; a linear or branched alkoxy chain; an alkenyloxy chain;a salified or non-salified sulfate group; a salified or non-salifiedsulfonyl group; a salified or non-salified phosphonate group; a salifiedor non-salified phosphate group; or a silanol group in which one or morecarbon-based chains may be substituted.
 2. The method of claim 1 whereinthe compound has the formula (III) in which n=2.
 3. The method of claim2 wherein the compound has the following formula (IVa)

wherein R₆ and R₇ are as defined in claim
 1. 4. The method of claim 3,wherein R₆ is a hydroxyl group and R₇ is a hydrogen atom.
 5. The methodof claim 1, wherein the compound is extracted from a plant.
 6. Themethod of claim 1, wherein the topical composition further comprises atleast one topically acceptable excipient.
 7. The method of claim 1,wherein the topical composition is a cosmetic composition.
 8. The methodof claim 7, wherein the cosmetic composition further comprises at leastone other cosmetically active ingredient.
 9. The method of claim 1,wherein the topical composition is a pharmaceutical composition for thetreatment of hyperpigmentation.
 10. A method of cosmetic care,comprising topically applying a cosmetic composition to at least onearea of the skin tissue of an individual having hyperpigmentation,wherein the cosmetic composition comprises an amount of a compound offormula (III)

effective to reduce skin pigmentation in the area of application,wherein Z represents an oxygen or an —NH— group; X and Y are identicaland each represent a CH group (cis or trans) or CH₂ group; n is anumber, preferably an integer, ranging from 1 to 12; R₂, R₃, R₆ and R₇are, independently of each other: a hydrogen atom; a hydroxyl group; ahalogen atom; a salified or non-salified acid function; an aldehydefunction; an amide function; a primary, secondary, or tertiary aminefunction in basic or salified form; a cyano group; a thiol group; anitro group; a sugar; an O-heteroside; a linear or branched alkoxidegroup; a linear or branched alkyl chain; a linear or branched alkenylchain; a linear or branched thioalkyl chain; a linear or branched alkoxychain; an alkenyloxy chain; a salified or non-salified sulfate group; asalified or non-salified sulfonyl group; a salified or non-salifiedphosphonate group; a salified or non-salified phosphate group; or asilanol group in which one or more carbon-based chains may besubstituted.
 11. The method of claim 10 wherein the compound has theformula (III) in which n=2.
 12. The method of claim 11 wherein thecompound has the following formula (IVa)

wherein R₆ and R₇ are as defined in claim
 1. 13. The method of claim 12,wherein R₆ is a hydroxyl group and R₇ is a hydrogen atom.
 14. The methodof claim 10, wherein the compound is extracted from a plant.
 15. Themethod of claim 10, wherein the cosmetic composition further comprisesat least one other cosmetically active ingredient.
 16. The method ofclaim 10, wherein the cosmetic composition further comprises at leastone topically acceptable excipient.
 17. A method of melanogenesisinhibition comprising topically applying to at least one area of skintissue in need of melanogenesis inhibition a composition comprising anamount of a compound of formula (III)

effective to inhibit melanogenesis, wherein Z represents an oxygen or an—NH— group; X and Y are identical and each represent a CH group (cis ortrans) or CH₂ group; n is a number, preferably an integer, ranging from1 to 12; R₂, R₃, R₆ and R₇ are, independently of each other: a hydrogenatom; a hydroxyl group; a halogen atom; a salified or non-salified acidfunction; an aldehyde function; an amide function; a primary, secondary,or tertiary amine function in basic or salified form; a cyano group; athiol group; a nitro group; a sugar; an O-heteroside; a linear orbranched alkoxide group; a linear or branched alkyl chain; a linear orbranched alkenyl chain; a linear or branched thioalkyl chain; a linearor branched alkoxy chain; an alkenyloxy chain; a salified ornon-salified sulfate group; a salified or non-salified sulfonyl group; asalified or non-salified phosphonate group; a salified or non-salifiedphosphate group; or a silanol group in which one or more carbon-basedchains may be substituted.
 18. The method of claim 17 wherein thecompound has the formula (III) in which n=2.
 19. The method of claim 18wherein the compound has the following formula (IVa)

wherein R₆ and R₇ are as defined in claim
 1. 20. The method of claim 19,wherein R₆ is a hydroxyl group and R₇ is a hydrogen atom.
 21. The methodof claim 17, wherein the compound is extracted from a plant.
 22. Themethod of claim 17, wherein the composition is a cosmetic composition.23. The method of claim 22, wherein the cosmetic composition furthercomprises at least one other cosmetically active ingredient.
 24. Themethod of claim 17, wherein the composition further comprises at leastone topically acceptable excipient.
 25. The method of claim 17, whereinthe composition is a pharmaceutical composition for the treatment ofhyperpigmentation.